Final answer:
Enzymes speed up chemical reactions by lowering the activation energy, which allows cellular reactions to proceed rapidly and efficiently. The rate of reactions can be decreased by changing temperatures, concentrations, and pH levels.
Step-by-step explanation:
Enzyme Function
Enzymes are biological molecules that act as catalysts, which means they speed up chemical reactions without being consumed or permanently altered by the reaction themselves. They achieve this by lowering the activation energy, which is the energy required to start a reaction. This process allows reactions within the cellular environment to occur faster and more efficiently than they would without the enzyme. An enzyme's active site binds to its substrate, which is the specific reactant the enzyme acts on, leading to a chemical reaction. Enzymes are highly specific for their substrates due to the unique shape and chemical environment of their active sites.
Decreasing the Rate of Chemical Reactions
The rate of chemical reactions can be decreased by changing specific conditions such as lowering temperature, reducing substrate concentration, and altering pH levels. For instance, storing food in a refrigerator at lower temperatures reduces the rate of spoilage reactions. In an enzyme-catalyzed reaction, increasing the substrate concentration initially increases the reaction rate, but it eventually begins to level off. At very high temperatures or unsuitable pH levels, enzymes can become inactive, lowering the rate of the reactions they catalyze.